"""
JSONSchema linting for YAML documents.
"""
import logging
import typing as t
from enum import Enum
from io import StringIO
import re
import yaml
from yaml.nodes import MappingNode, Node, ScalarNode, SequenceNode
log = logging.getLogger(__name__)
class LintLevel(Enum):
"""Lint outcome levels."""
MISSING = 1
MISSMATCH = 2
UNEXPECTED = 3
class LintRecord(t.NamedTuple):
"""A linting record."""
level: LintLevel
node: Node
schema: object
message: str
@property
def start_mark(self):
return self.node.start_mark
class YamlLinter(object):
"""YAML linting against JSON schemas."""
def __init__(self, schema):
self._schema = schema
def dereference(self, schema):
"""Dereference a {"$ref": ""} form."""
if ref := schema.get("$ref"):
assert ref.startswith("#/")
path = ref.lstrip("#/").split("/")
schema = self._schema
for e in path:
if not (schema := path.get(e)):
raise ValueError(f"Unable to dereference {ref}")
return schema
def lint_mapping(self, schema, node: Node) -> t.Iterable[str]:
"""FIXME.
"""
if schema["type"] != "object" or not isinstance(node, MappingNode):
yield LintRecord(
LintLevel.MISSMATCH,
node,
schema,
f"Expected {schema['type']}, got {node.id} {str(node.start_mark).lstrip()}",
)
additional_type: t.Union[dict, bool] = (
schema.get("additionalProperties", True)
)
properties: dict = schema.get("properties", {})
required: t.Iterable[str] = schema.get("required", [])
for k in required:
if k not in [_k.value for _k, _v in node.value]:
yield LintRecord(
LintLevel.MISSING,
node,
schema,
f"Required key {k!r} absent from mapping {str(node.start_mark).lstrip()}",
)
for k, v in node.value:
if k.value in properties:
yield from self.lint_document(properties.get(k.value), v)
elif additional_type:
yield from self.lint_document(additional_type, v)
else:
yield LintRecord(
LintLevel.UNEXPECTED,
node,
schema,
f"Key {k.value!r} is not allowed by schema {str(node.start_mark).lstrip()}",
)
def lint_sequence(self, schema, node: Node) -> t.Iterable[str]:
"""FIXME.
There aren't sequences we need to lint in the current schema design, punting.
"""
if schema["type"] != "array" or not isinstance(node, SequenceNode):
yield LintRecord(
LintLevel.MISSMATCH,
node,
schema,
f"Expected {schema['type']}, got {node.id} {str(node.start_mark).lstrip()}",
)
subschema = schema.get("items")
if subschema:
for item in node.value:
yield from self.lint_document(subschema, item)
def lint_scalar(self, schema, node: Node) -> t.Iterable[str]:
"""FIXME.
The only terminal we care about linting in the current schema is {"type": "string"}.
"""
if schema["type"] == "string":
yield from self.lint_string(schema, node)
elif schema["type"] == "integer":
yield from self.lint_integer(schema, node)
elif schema["type"] == "number":
yield from self.lint_number(schema, node)
else:
raise NotImplementedError(
f"Scalar type {schema['type']} is not supported"
)
def lint_string(self, schema, node: Node) -> t.Iterable[str]:
"""FIXME."""
if node.tag != "tag:yaml.org,2002:str":
yield LintRecord(
LintLevel.MISSMATCH,
node,
schema,
f"Expected a string, got a {node}"
)
if maxl := schema.get("maxLength"):
if len(node.value) > maxl:
yield LintRecord(
LintLevel.MISSMATCH,
node,
schema,
f"Expected a shorter string"
)
if minl := schema.get("minLength"):
if len(node.value) < minl:
yield LintRecord(
LintLevel.MISSMATCH,
node,
schema,
f"Expected a longer string"
)
if pat := schema.get("pattern"):
if not re.fullmatch(pat, node.value):
yield LintRecord(
LintLevel.MISSMATCH,
node,
schema,
f"Expected a string matching the pattern"
)
def lint_integer(self, schema, node: Node) -> t.Iterable[str]:
if node.tag == "tag:yaml.org,2002:int":
value = int(node.value)
yield from self._lint_num_range(schema, node, value)
else:
yield LintRecord(
LintLevel.MISSMATCH,
node,
schema,
f"Expected an integer, got a {node}"
)
def lint_number(self, schema, node: Node) -> t.Iterable[str]:
if node.tag == "tag:yaml.org,2002:float":
value = float(node.value)
yield from self._lint_num_range(schema, node, value)
else:
yield LintRecord(
LintLevel.MISSMATCH,
node,
schema,
f"Expected an integer, got a {node}"
)
def _lint_num_range(self, schema, node: Node, value) -> t.Iterable[str]:
""""FIXME."""
if base := schema.get("multipleOf"):
if value % base != 0:
yield LintRecord(
LintLevel.MISSMATCH,
node,
schema,
f"Expected a multiple of {base}, got {value}"
)
if max := schema.get("exclusiveMaximum"):
if value >= max:
yield LintRecord(
LintLevel.MISSMATCH,
node,
schema,
f"Expected a value less than {max}, got {value}"
)
if max := schema.get("maximum"):
if value > max:
yield LintRecord(
LintLevel.MISSMATCH,
node,
schema,
f"Expected a value less than or equal to {max}, got {value}"
)
if min := schema.get("exclusiveMinimum"):
if value <= min:
yield LintRecord(
LintLevel.MISSMATCH,
node,
schema,
f"Expected a value greater than {min}, got {value}"
)
if min := schema.get("minimum"):
if value < min:
yield LintRecord(
LintLevel.MISSMATCH,
node,
schema,
f"Expected a value greater than or equal to {min}, got {value}"
)
def lint_document(self, node, schema=None) -> t.Iterable[str]:
"""Lint a document.
Given a Node within a document (or the root of a document!), return a
(possibly empty!) list of lint or raise in case of fatal errors.
"""
schema = schema or self._schema # Fixing up the schema source
schema = self.dereference(schema) # And dereference it if needed
if schema == True or schema == {}:
yield from []
elif isinstance(node, MappingNode):
yield from self.lint_mapping(schema, node)
elif isinstance(node, SequenceNode):
yield from self.lint_sequence(schema, node)
elif isinstance(node, ScalarNode):
yield from self.lint_scalar(schema, node)
else:
yield from []
def lint_node(schema, node, cls=YamlLinter):
"""Lint a document using a schema and linter."""
print(repr(node))
linter = cls(schema)
yield from linter.lint_document(node)
def lint_buffer(schema, buff: str, cls=YamlLinter):
"""Lint a buffer (string)."""
with StringIO(buff) as f:
node = yaml.compose(f)
yield from lint_node(schema, node, cls=cls)
def lint_file(schema, path, cls=YamlLinter):
"""Lint a file."""
with open(path) as f:
node = yaml.compose(f)
yield from lint_node(schema, node, cls=cls)